JP4351595B2 - Method for forming a copper wiring layer - Google Patents

Description

  The present invention generally relates to semiconductor device wiring technology, and more particularly to a method of forming a copper wiring layer.

Conventionally, aluminum wiring layers have been widely used for semiconductor device wiring. However, from the viewpoints of high performance, high speed, and miniaturization of semiconductor devices, copper wiring layers will be used for future semiconductor device wiring. Promising to use. However, it is difficult to form a pattern in a copper wiring layer by dry etching like an aluminum wiring. For this reason, the copper wiring layer is formed by recessing an insulating substrate, forming a trench or groove in a desired shape, and filling the recess with copper. The filling of copper is performed using an electrolytic plating method. This type of plating method is disclosed in Patent Documents 1 and 2.
JP 11-315385 A JP 11-315395 A

  By the way, as a semiconductor device is miniaturized, it is often necessary to provide a wide wiring near a dense fine wiring. That is, grooves having different aspect ratios are formed relatively close to each other. The aspect ratio is determined by, for example, the depth of the groove and the size of the opening.

  FIG. 1 shows a state in which a wide wiring is formed near a dense fine wiring. As shown in the drawing, the semiconductor substrate is arranged with a first region 10 having a bottom of about 3 μm and a first recess having a depth of about 0.3 μm, for example, with a pitch of about 0.1 μm, for example. The second region 20 having a plurality of second depressions having a depth of about 0.3 μm is formed in the semiconductor substrate or the interlayer insulating film. The left side of FIG. 1 shows a state in which a copper wiring layer is formed on such a semiconductor structure by an electroplating method in a conventional manner. In this case, in the first region 10 including the depression having the wide opening, the undulations 12 corresponding to the depression are reflected in the conductive layer, while in the second region 20 in which the depression having the narrow opening is arranged, on the contrary, It is known that a conductive layer 22 having a raised shape 22 is formed on the two regions 20. Such a step is generated in the conductive layer because a plating method called a bottom-up method or an overfilling method is employed. In the bottom-up method, a predetermined additive is introduced into the plating solution so that copper can be sufficiently filled even in a narrow and deep groove. Of the conductive layer having such undulations, a region lower in height than a conductive layer (having a surface having a height indicated by a broken line in the drawing) laminated on a reference surface where no depression or groove is formed, It is called the under plate, and the high altitude area is called the over plate. By adding a certain additive to the plating solution, it is possible to perform plating with excellent filling properties, but on the other hand, a step due to the over plate and the under plate is formed in the conductive layer. After the conductive layer is deposited, the conductive layer is polished and planarized by, for example, chemical mechanical polishing (CMP) to form a wiring layer.

  However, if the above-described under plate is excessively formed, the conductive layer in the first region 10 may be improperly recessed and polished as shown in the right side of FIG. Such a phenomenon is known as dishing, and there is a concern that a wiring defect may occur or a semiconductor device having a multilayer wiring structure may be distorted.

  In order to avoid such inconvenience due to dishing, conventionally, a copper conductive layer is formed sufficiently thick. As shown on the left side of FIG. 2, for example, a copper wiring layer is laminated with a thickness of 3 or 4 times the depth of the groove, and then flattened, and as shown on the right side of FIG. 2. A good wiring layer is formed.

  However, increasing the thickness of the copper wiring layer is advantageous from the standpoints that a larger amount of film forming material is required, a longer time is required for the plating process and polishing process, and throughput is deteriorated. is not.

  The present invention has been made in view of the above problems, and the problem is that a plurality of depressions having a first region having at least one depression and an aspect ratio different from the aspect ratio of the at least one depression. To provide a method of forming a copper wiring layer at a low cost in a semiconductor structure having a second region lined up individually.

In the present invention,
A first step of forming a copper conductive layer with a plating solution having a first sulfuric acid concentration in a semiconductor structure having two or more grooves having different line widths;
A second step of laminating a conductive layer on the conductive layer with a plating solution having a second sulfuric acid concentration lower than the first sulfuric acid concentration;
And a polishing step of polishing the copper conductive layer formed on the semiconductor structure. A method of forming a copper wiring layer is used.

  According to the present invention, a copper wiring layer can be formed at a low cost in a semiconductor structure having two or more grooves having different line widths.

  According to one aspect of the present invention, a copper conductive layer is formed in a semiconductor structure having two or more grooves having different line widths with a plating solution having a first sulfuric acid concentration, and the first conductive layer is thinner than the first sulfuric acid concentration. A conductive layer is further laminated with a plating solution having a sulfuric acid concentration of 2. The plating process is performed in two stages. In the first process, the narrow-width groove is completely filled with copper, and in the second process, the conductive layer is formed while suppressing the under plate. Thereby, a copper wiring structure having a wide wiring near a plurality of dense fine wirings can be formed at a low cost.

  According to one aspect of the present invention, the total film thickness of the conductive layer at least at the start of the polishing step is less than twice the depth of any groove. Since the under plate is sufficiently suppressed in the film formation in the second step, it is possible to suppress the occurrence of dishing during the subsequent planarization even if the conductive layer is made thinner than the conventional one.

  According to one aspect of the present invention, the concentration of the sulfur compound added to the plating solution having the first sulfuric acid concentration is higher than the concentration of the sulfur compound added to the plating solution having the second sulfuric acid concentration. thin. Further, the molecular weight of the amine compound added to the plating solution having the first sulfuric acid concentration is smaller than the molecular weight of the amine compound added to the plating solution having the second sulfuric acid concentration. Furthermore, the amount of the amine compound added to the plating solution having the first sulfuric acid concentration is less than the amount of the amine compound added to the plating solution having the second sulfuric acid concentration. By employing such an additive, plating can be performed while conveniently suppressing the overplate and underplate in the second step, and the step of the conductive layer can be reduced.

  FIG. 3 shows a schematic apparatus for performing a plating method according to an embodiment of the present invention. The apparatus includes plating cells 302, 302 ″, a first plating tank 304, a controller 306, first additive tanks 308-1, 310-1, 312-1, and a second plating tank 314. , Second additive tanks 308-2, 310-2, 312-2, anodes 316, 316 "and power supplies 318, 318".

  In the plating cells 302 and 302 ″, plating solutions from the first and second plating tanks 304 and 314 are stored. The substrate 320 is immersed in a plating solution, and a voltage is applied between the substrate 320 and the anodes 316, 316 ", whereby electrolytic plating is performed on the substrate 320. Additives from the first additive tank or additive supply units 308-1, 310-1, 312-1 are introduced into the plating solution in the first plating tank 304. The controller 306 monitors the state or composition of the plating solution in the plating tank 304 and adjusts the amount of additive supplied from each of the additive tanks so that the state is constant. The plating solution in the first plating tank is introduced into the plating cell 302 by opening the valves 305 and 307, and the plating cell 302 and the first plating tank 304 are separated by closing them. Similarly, the additive from the second additive tanks 308-2, 310-2, 312-2 is introduced into the plating solution in the second plating tank 314. The controller 306 monitors the state or composition of the plating solution in the plating tank 314 and adjusts the amount of additive supplied from each of the additive tanks so that the state is constant. The plating solution in the second plating tank is introduced into the plating cell 302 ″ by opening the valves 315 and 317, and the plating cell 302 ″ and the second plating tank 314 are separated by closing them. .

  FIG. 4 shows a main process diagram of a method of forming a copper wiring layer according to this embodiment. As shown in FIG. 4A, first, a semiconductor substrate 320 having an interlayer insulating film 40 is prepared. For simplicity, the base of the interlayer insulating film 40 is not shown in FIG. The interlayer insulating film 40 is arranged with a first region 10 having a bottom of about 3 μm and a first recess having a depth of about 0.3 μm, for example, at a pitch of about 0.1 μm, and each is about 0.3 μm. A second region 20 having a plurality of second depressions having a depth of 2 mm is formed in the semiconductor substrate or the interlayer insulating film. A copper seed layer is formed on the substrate having such a structure having the first and second regions, for example, by sputtering (not shown). The substrate 320 on which the seed layer is formed is connected to the power source 318 in FIG. 3 and immersed in the plating solution, and as shown in FIG. 4A, the first conductive layer is formed on the first and second regions. 42 is deposited. For convenience of explanation, the process shown in FIG. 4A is called a first plating process. This film forming process is continued until a plurality of fine depressions in the second region are completely filled with copper. As a result, a raised shape of the conductive layer is formed on the second region 20, and an overplate is formed. In the first region 10, an under plate is formed.

In the process of FIG. 4A, the plating solution supplied from the first plating tank 304 is supplied to the plating tank 302, and the plating solution is composed of a basic bath (VMS: virgin make-up solution) and an additive, The basic bath contains copper sulfate (CuSO ₄ ), sulfuric acid (H ₂ SO ₄ ), and hydrochloric acid (HCl) as main components. Additives are mainly composed of brightener that promotes copper film growth (brightener), inhibitor (polymer) that suppresses copper film growth, and smoothing agent (leveler) that smoothes the film. Also called agent, B agent and C agent. Agent A is a sulfur compound. The B agent is a polymer such as polyethylene glycol or polypropylene glycol. The agent C is an amine compound. By adding these additives to the basic bath, it is possible to perform plating with excellent filling properties, but on the other hand, a step due to the above-described over plate and under plate is formed in the conductive layer. .

  In the step shown in FIG. 4B, the second plating step is performed. Next, by opening the valves 315 and 317, the plating solution in the second plating tank 314 is supplied to the plating cell 302 ″. As will be described later, the plating solution in the second step is the plating in the first step. It has a thinner sulfuric acid concentration, a thinner additive concentration of agent A, and a higher molecular weight agent C. The copper second conductive layer 44 is electrolyzed on the first conductive layer 42. The underplate can be made smaller by performing electroplating under the above conditions, as shown in Fig. 5 when only the process of Fig. 4B is performed. The conductive layer 44 'to be formed and the conductive layer 43 formed by a conventional method are shown as shown in Fig. 5. As shown in Fig. 5, the underplate of the conductive layer formed in the second step of Fig. 4B. Is smaller than that of a conductive layer deposited by conventional methods .

  In the step shown in FIG. 4C, the copper wiring layer is formed by smoothing the copper conductive layer by a chemical mechanical polishing (CMP) method. Since the under plate formed in the process of FIG. 4B is smaller than the conventional one, dishing that has been a concern in the past is suppressed.

  The inventors of the present invention have obtained a measurement result as shown below in basic research related to the present application, and have found a copper film forming method that is convenient for suppressing the above-described under plate. In the following, various experimental results relating to an advantageous film forming method are shown.

  In the experiment, (1) the ratio of the A agent and C agent added to the basic bath (VMS), (2) the concentration of sulfuric acid contained in the basic bath, and (3) the structure of the C agent were variously changed.

(1) Ratio of A agent and C agent FIG. 6: is a chart which shows nine conditions which changed the ratio of A agent and C agent into nine types. The additive ratio (ml / L) in the first step is set to 100% (reference value). Through the first and second steps, the concentration of copper ions in the basic bath is 40 g / L, the concentration of sulfuric acid is 40 g / L, and the concentration of chlorine ions is 50 ppm. Conditions 1 to 5 are such that the ratio of the A agent is changed within the range of 0% to 200% when the ratio of the B agent and the C agent is constant. Since the agent A has a property of promoting copper film formation, it can be expected that the overplate can be reduced by reducing the ratio. In conditions 6 to 9, when the ratio of agent A and agent B is constant, the ratio of agent C is changed. Since the agent C has a property of suppressing copper film formation, it can be expected that the overplate can be reduced by increasing the ratio. The reason why the B agent is made constant by changing the ratio of the A agent and the C agent is that the A agent and the C agent are expected to have a greater influence on the copper growth than the B agent.

FIG. 7 shows the measurement results of the underplate and bottom-up rate of the conductive layer formed by performing the second step under the nine conditions shown in FIG. Here, the bottom-up rate is
((Film thickness b grown at the bottom of the groove) − (film thickness a grown outside the groove)) / (film thickness a grown outside the groove)
The film thicknesses a and b are film thicknesses at locations as shown in FIG. For example, in the second step, when the conductive layer is formed to the same extent inside and outside the groove, b = a and the bottom-up rate is 0 (%). Conversely, when the conductive layer is formed in the groove twice as large as the outside of the groove, b = 2a and the bottom-up rate is 100%. Note that the total film thickness by the first and second steps outside the groove is referred to as the film thickness c, and in the following numerical example, c = 520 nm and c−a = 297 nm. In FIG. 7, a 297 nm under plate is formed in the first step, and when the second step is performed by the conventional method (when the second plating is performed under the same conditions as the first step), a 304 nm under plate is formed. It is formed. In this case, the bottom-up rate is −3.9%, and the under plate is increased. As shown in the drawing, it can be seen that the under plate of the conditions 3 and 6 is low and the bottom-up rate is also good. FIG. 9 shows a bar graph with the under plate shown in FIG. 7 taken on the vertical axis. From these experimental results, it can be seen that reducing the A agent that promotes film formation of copper and / or increasing the C agent that suppresses film formation contributes to the suppression of the under plate and the like.

(2) Concentration of sulfuric acid FIG. 10 shows the case where the sulfuric acid concentration in the second step is 20, 40 and 60 (g / L), and the concentrations of the A, B and C agents are the conditions 3 and 4 in FIG. And 6 (relatively large effects). In the first step, a plating solution having a sulfuric acid concentration of 40 (g / L) is used.

  FIG. 11 shows the measurement results of the underplate and bottom-up rate of the conductive layer formed by performing the second step under the various conditions shown in FIG. FIG. 12 is a bar graph depicting the measurement results of the under plate of FIG. As shown in the drawing, when the sulfuric acid concentration in the second step is the same as or lower than that in the first step, the under plate is reduced and the bottom-up rate is improved. In particular, in the case where the sulfuric acid concentration in the second step is thinner than that in the first step, and corresponding to the condition 4, the under plate is particularly small, and the bottom-up rate is greatly improved.

  As the concentration of sulfuric acid increases, the conductivity in the plating solution is improved, the copper film formation is promoted, and the overplate is expected to be enlarged. Conversely, when the concentration of sulfuric acid is reduced, copper film formation is suppressed, and overplate is expected to be suppressed. On the other hand, depending on the line width of the copper wiring, an over plate occurs in a narrow groove portion, and an under plate occurs in a wide groove portion. Therefore, suppressing the over plate also suppresses the under plate. From such consideration, it is predicted that the lower the concentration of sulfuric acid, the more advantageous from the viewpoint of suppressing the under plate.

(3) Structure of C agent In the experimental example shown below, the molecular structure of the C agent (amine compound) added to the basic bath of the plating solution used in the second step is expressed as C ₁ , C ₂ , C _3. It is changed to three types. The molecular weights of the respective C agents are M _C1 , M _C2 , and M _C3 , respectively (M _C3 <M _C1 <M _C2 ). FIG. 13 shows various conditions when the concentrations of the A, B, and C agents are the conditions 3, 4 and 6 in FIG. 7 for each of the various C agents (C ₁ , C ₂ , C ₃ ). The agent C has a function of suppressing copper film formation. The suppressive power of the additives C ₂ and C ₃ used in this example is stronger than the suppressive power of the additive C ₁ . In the first step, additives C ₁ is added to the basic bath.

FIG. 14 shows the measurement results of the underplate and bottom-up rate of the conductive layer formed by performing the second step under the various conditions shown in FIG. FIG. 15 is a bar graph depicting the measurement results of the under plate of FIG. As shown in the figure, the additive C ₃ has a lower under plate and bottom-up rate, although the film formation suppression force is stronger than the additive C ₁ . On the other hand, when the molecular weight of the C agent in the second step is larger than that in the first step (when the molecular weight is _MC2 ), the under plate is reduced and the bottom-up rate is improved. Among them, the one related to the condition 4 is that the under plate is particularly small and the bottom-up rate is greatly improved. Therefore, it can be seen that it is more advantageous to improve the bottom-up ratio and the like for the C agent than to select a C agent having a large film weight suppressing force, rather than selecting a C agent having a strong film-forming suppression force.

  As described above, the agent C works to suppress copper film formation. A diffusion layer is formed between the conductive layer in the middle of the film formation and the plating solution, and the C agent diffuses in the diffusion layer, reaches the conductive layer, and acts to suppress film formation. The relatively low molecular weight C agent diffuses quickly, thus promoting underplate. The C agent having a large molecular weight has a low diffusion rate, and therefore suppresses the under plate.

(4) Sulfuric acid concentration and structure of C agent FIG. 16 shows that the C agent used in the second step is C ₁ (molecular weight M _C1 ) and C ₂ (molecular weight M _C2 > M _C1 ), and the sulfuric acid concentration is 20 g / The conditions when the concentrations of the A, B, and C agents are L, 3, 4, and 6 in FIG. In the first step, a basic bath having a sulfuric acid concentration of 40 g / L is used, and a C agent having a molecular weight M _C1 is added to the basic bath.

  FIG. 17 shows the measurement results of the under plate and the bottom-up rate of the conductive layer formed by performing the second step under the various conditions shown in FIG. FIG. 18 is a bar graph showing the measurement results of the under plate of FIG. As shown in the drawing, when the sulfuric acid concentration in the second step is lower and the molecular weight of the C agent is larger than that in the first step, the under plate is particularly small, and the bottom-up rate is greatly improved.

  According to the present embodiment, the copper plating process is divided into a first process and a second process. In the second process, a basic bath having a lower sulfuric acid concentration is used, and a C agent having a large molecular weight is added to the basic bath. Thus, overplate and underplate of the copper conductive layer can be suppressed. Thereby, even if the conductive layer formed in the plating step is thinner than the conventional one, the conductive layer can be planarized without causing dishing. For example, conventionally, it has been necessary to form a conductive layer having a thickness of about 1 μm, which is 3 to 4 times as large as a groove of about 0.3 μm, but according to this embodiment, a thickness of about 0.5 μm ( 520 nm), even with a film thickness thinner than twice the depth of the groove, good planarization can be performed. Therefore, the cost for forming the copper wiring layer is greatly improved.

  19 and 20 show a method of forming a copper wiring layer according to an embodiment of the present invention. In this embodiment, the plating method as described in Embodiment 1 is used for the multilayer wiring structure of the semiconductor device.

  In the step shown in FIG. 19A, conductive layers 1904 and 1906 are already formed in the interlayer insulating film 1902. The interlayer insulating film 1902 may be a semiconductor substrate. Further, a further interlayer insulating film 1908 is formed on the interlayer insulating film 1902. In the interlayer insulating film 1908, vias (also referred to as grooves, trenches, depressions, etc.) are formed at locations where copper wiring layers are to be formed later. In the first region 1912 on the right side in the drawing, one via having a wide opening is formed, and in the second region 1922 on the left side in the drawing, a plurality of elongated vias having narrow openings are formed.

  In the step shown in FIG. 19B, a barrier metal 1924 is formed on the entire surface of the structure. For the barrier metal 1924, a conductive material such as tantalum nitride (TaN), titanium nitride (TiN), tungsten (W), or the like may be used. The barrier metal 1924 is for suppressing the later filled copper from diffusing into the interlayer insulating film 1908. Further, a copper seed 1926 is formed on the barrier metal 1924. The seed 1926 functions as one of electrodes when performing plating. The barrier metal 1924 and the seed 1926 can be formed using a thin film forming technique known in the art such as a sputtering method or a CVD method.

  In the step shown in FIG. 19C, the first step of the plating step performed in two stages is performed. The plating solution is obtained by adding additives (agent A, agent B and agent C) to the basic bath (VMS). In this first step, the plurality of vias in the second region 1922 are completely filled with the copper conductive layer 1928. An over plate is generated in the second region 1922 and an under plate is generated in the first region 1912 mainly due to the action of the additive.

  In the step shown in FIG. 20D, the second step of the plating step is performed. The plating solution in this case is different from the plating solution in the first step. The sulfuric acid concentration of the plating solution used in the second step is thinner than that in the first step. Moreover, the molecular weight of the C agent added to the plating solution in the second step is larger than that in the first step. By performing the second plating step with such a plating solution, a conductive layer 1930 in which overplate and underplate are suppressed is formed on the conductive layer 1928.

  In the step shown in FIG. 20E, the conductive layers 1928 and 1930 are planarized. For the planarization, for example, a chemical mechanical polishing (CMP) method can be used.

  In the step shown in FIG. 20F, the cap layer 1932 is formed over the entire surface. For the cap layer 1932, an insulating material such as silicon carbide (SiC), SiOC, or SiO can be used. Also in this embodiment, the under plate of the conductive layer 1930 is suppressed to be small, and the total thickness of the conductive layers 1928 and 1930 can be thin, so that copper wiring layers having different line widths can be formed at low cost.

  Hereinafter, the means taught by the present invention will be listed as an example.

(Appendix 1)
A first step of forming a copper conductive layer with a plating solution having a first sulfuric acid concentration in a semiconductor structure having two or more grooves having different line widths;
A second step of laminating a conductive layer on the conductive layer with a plating solution having a second sulfuric acid concentration lower than the first sulfuric acid concentration;
And a polishing step of polishing the copper conductive layer formed on the semiconductor structure.

(Appendix 2)
The method according to claim 1, wherein the total film thickness of the conductive layer at least at the start of the polishing step is thinner than twice the depth of an arbitrary groove.

(Appendix 3)
Appendix 1 characterized in that the concentration of the sulfur compound added to the plating solution having the first sulfuric acid concentration is different from the concentration of the sulfur compound added to the plating solution having the second sulfuric acid concentration. The method described.

(Appendix 4)
The supplementary note 1, wherein the concentration of the sulfur-based compound added to the plating solution having the first sulfuric acid concentration is lower than the concentration of the sulfur-based compound added to the plating solution having the second sulfuric acid concentration. the method of.

(Appendix 5)
The molecular weight of the amine compound added to the plating solution having the first sulfuric acid concentration is different from the molecular weight of the amine compound added to the plating solution having the second sulfuric acid concentration. the method of.

(Appendix 6)
The molecular weight of the amine compound added to the plating solution having the first sulfuric acid concentration is smaller than the molecular weight of the amine compound added to the plating solution having the second sulfuric acid concentration. the method of.

(Appendix 7)
The amount of the amine compound added to the plating solution having the first sulfuric acid concentration is different from the amount of the amine compound added to the plating solution having the second sulfuric acid concentration. the method of.

(Appendix 8)
The amount of the amine compound added to the plating solution having the first sulfuric acid concentration is less than the amount of the amine compound added to the plating solution having the second sulfuric acid concentration. the method of.

(Appendix 9)
In the first step, a conductive layer raised in a region including a groove having a narrow line width is formed, and a conductive layer having a shape recessed according to the groove having a wide line width is formed. the method of.

(Appendix 10)
A method of manufacturing a semiconductor device using the method for forming a copper wiring layer described in Appendix 1.

It is a figure which shows the mode of the film-forming and planarization of the wiring layer of a wide and narrow width. It is a figure which shows the mode of the film-forming and planarization of the wiring layer of a wide and narrow width. It is a figure which shows the apparatus for performing the plating by one Example of this invention. It is process drawing which shows the plating method by one Example of this invention. It is a figure which shows the difference between the conductive layer formed at the process of FIG.4 (b), and the conductive layer formed by the conventional method. It is a graph which shows the ratio of A agent, B agent, and C agent contained in the additive used for experiment. It is a graph which shows the measured value of the underplate and bottom-up rate of the conductive layer formed into a film using various additives. It is a figure which shows the correlation of film thickness a, b, c relevant to a bottom-up rate. It is a figure which shows the magnitude | size of the underplate shown by FIG. 7 with a bar graph. It is a graph which shows the ratio of the sulfuric acid concentration used for experiment, and the A agent, B agent, and C agent contained in an additive. It is a graph which shows the measured value of the underplate and bottom-up rate of the conductive layer formed into a film using various additives. It is a figure which shows the magnitude | size of the underplate shown by FIG. 11 with a bar graph. It is a graph which shows the kind of C agent used for experiment, and the ratio of A agent, B agent, and C agent contained in an additive. It is a graph which shows the measured value of the underplate and bottom-up rate of the conductive layer formed into a film using various additives. It is a figure which shows the magnitude | size of the underplate shown by FIG. 14 with a bar graph. It is a graph which shows the ratio of the sulfuric acid concentration used for experiment, the kind of C agent, and the A agent, B agent, and C agent contained in an additive. It is a graph which shows the measured value of the underplate and bottom-up rate of the conductive layer formed into a film using various additives. It is a figure which shows the magnitude | size of the underplate shown by FIG. 17 with a bar graph. It is FIG. (1) which shows the method of forming the multilayer wiring by one Example of this invention. FIG. 6 is a second diagram illustrating a method of forming a multilayer wiring according to an embodiment of the present invention.

Explanation of symbols

10 first region; 20 second region;
302 plating cell; 304, 314 plating tank; 306 controller; 308, 310, 312 additive supply; 305, 307, 315, 317 valve; 318 power supply; 320 material to be plated;
40 interlayer insulating film; 42, 43, 44, 44 'conductive layer;
1902 Interlayer insulating film; 1904, 1906 Wiring layer; 1908 Interlayer insulating film; 1912 1st region; 1922 2nd region; 1924 Barrier metal; 1926 Seed layer; 1928, 1930 Copper conductive layer; 1932 Cap layer

Claims (4)

A method of forming a copper wiring layer on a semiconductor structure having two or more grooves having different line widths by an electrolytic plating method, wherein the plating solution used in the electrolytic plating method is mainly composed of copper sulfate, sulfuric acid and hydrochloric acid. In the basic bath, a brightener containing a sulfur compound, a deterrent containing a polymer and a smoothing agent containing an amine compound are added,
A first step of forming a conductive layer of copper plating solution having a first sulfuric acid concentration in the semiconductor structure,
A second step of laminating a conductive layer on the conductive layer with a plating solution having a second sulfuric acid concentration lower than the first sulfuric acid concentration;
The have a polishing step of polishing the conductive layer of the deposited copper on a semiconductor structure, concentration, said second concentration sulfuric sulfur-based compound added to the plating solution having a first concentration of sulfuric acid A method for forming a copper wiring layer, wherein the concentration is higher than the concentration of a sulfur-based compound added to a plating solution having a composition . The method according to claim 1, wherein the total thickness of the conductive layer at least at the start of the polishing step is thinner than twice the depth of an arbitrary groove. The molecular weight of the amine compound added to the plating solution having the first sulfuric acid concentration is smaller than the molecular weight of the amine compound added to the plating solution having the second sulfuric acid concentration. The method described. The amount of the amine compound added to the plating solution having the first sulfuric acid concentration is less than the amount of the amine compound added to the plating solution having the second sulfuric acid concentration. The method described.

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